The disclosure of this invention is to be contrasted with and compared to the disclosure of the invention in U.S. Pat. No. 4,368,644, Wentzell, et al. issued Jan. 18, 1983. Further, as may appear appropriate, the disclosure of this patent is to be considered as incorporated in and made a part of this present disclosure. Clearly, both inventions relate to apparatus with which to carry out the nondestructive ultrasonic inspection of nuclear reactor systems in adjacent locations.
For a utility operating a nuclear reactor system, it is imperative that Inservice Inspection (ISI) of the reactor system vessels be performed as rapidly as possible without sacrificing accuracy. The inspection system is comprised of mechanical positioning equipment and nondestructive examination instrumentation. It is desirable to reduce the time in making these inspections without reducing the quality of the examinations. Reduction in this time will enable the utility to realize savings in operating costs due to shorter downtimes and a reduction in radiation exposure to examination personnel.
The present rules for ISI, established by the ASME Code, Section XI "Rule for Inservice Inspection of Nuclear Power Plant Components", require a complete inspection of reactor vessel components every ten operational years. In addition it is a USNRC requirement that personnel radiation exposure be "as low as reasonably achievable." Hence, it is inevitable, based on these criteria and the very high cost of plant downtime, that an inspection must be carried out with reliable, accurate, and rapid techniques.
The inservice inspection program includes both the component and piping bodies. In general, there are numerous access problems, body configuration variations, and radiation hazards that must be considered. The inservice inspection tool may be mounted from the flange of the nuclear vessel and manipulated beneath many feet of radiation-shielding water. The area to be inspected in and about the nuclear vessel is reached with predetermined location information, supplemented by TV cameras. The ISI tool, from its mount on the reactor vessel flange, is capable of reaching all areas of the reactor vessel by actuating rotating and telescoping booms along with specially designed fixtures that hold nondestructive ultrasonic search units.
The operating console for this tool contains the necessary controls and instruments for manifesting readout information from the detectors. The controller allows the operator to move the search units accurately through all the required regions to be examined and provides precise position data. By enhancing the versatility of the inspection equipment, the number and frequency of mechanical configuration changes can be reduced. This has resulted in a reduction in setup time and, equally important, greatly reduced handling of contaminated parts. This versatility is achieved by means of remote or preprogramed positioning of ultrasonic transmitters and receivers.
There is a need for supporting linkage between an ultrasonic sound transmitter and receiver as the transmitter and receiver are swept about the surfaces of an inner radius lip of a nozzle in a nuclear reactor vessel. The linkage must accommodate the varying angle between the nozzle side and vessel side of the inner radius lip while simultaneously accommodating the saddle shape of the inner radius as the boom is rotated in a 360.degree. sweep.